Conservatives know that they don't like Elizabeth Warren, but they can't seem to decide why.

After weeks of slamming the Democratic Massachusetts Senate candidate as a radical class warrior, Republicans are trying a new line of attack. Crossroads GPS, the Karl Rove-funded super PAC, is out with a new ad this week that slams Warren for abandoning the middle class to get cozy with big banks.

The 30-second spot, "Champion," attempts to tie Warren to the TARP bailout, which feels like a little bit of a stretch. It also accuses her of going on a "charm offensive" with big banks, which is also a little farfetched.

Warren was quick to fire back:

"I can't find the right words to describe how wrong that is. Factually wrong and morally wrong," she told the Boston Herald. "Karl Rove is not telling the truth, and I think anyone who is not telling the truth shouldn't be running ads in this race."